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Taking Package DO reading

Hi everyone. I know this was discussed to some extent in older threads but I'm having a very specific issue involving the use of the Hamilton Beverly combined with a Zahm and Nagel piercing device. In a nutshell, we are trialling the equipment and cannot get an "accurate" DO reading from cans or bottles. The PPB measurement is sticking on 0, even if we pass the contents of 3＋ cans through the rig. I know this is a good piece of equipment & it is taking accurate readings during calibration.

Suspect it must be something with our technique:

>Can is pierced using Zahm and Nagel.

>Nitrogen gas pressure increased to force beer up inlet tube and into DO meter.

>Repeated with c. 3 cans

>No change in DO reading observed.

The main feeder tube to the DO meter is a significantly wider gauge than the piercing needle, could this be having an effect?

I've attached a pic of the overall process, let me know if you have any ideas, cheers!

I have used the Beverly DO meter extensively in a production brewery. They are not really suitable for testing packaged product, in my opinion, because you need to flow so much beer through the meter before the readings stabilize. In the manual it states that you need to flow at least 500 ml/minute for the first minute to purge the oxygen in the meter, then you can turn the flow down and it should take 1-3 minutes to get a stable reading. The temperature must be stable to get a stable DO reading. If you are trying to measure cold beer with a warm meter it takes much more time (and beer) to stabilize in my experience. These meters work well for measuring beer from a tank, but there are other more expensive meters that are more suitable for measuring DO in packaged product, such as the Hach orbisphere.

We had the same issue with ours. We were told by our rep that we needed to calibrate with higher spec nitrogen. So we went out and got a fill of 5.0 spec nitrogen for $250 and still the same problem. The meter is just inaccurate and shouldn't be considered in the same league as other top tier DO meters. Hamilton's customer service also stinks.